Smoke actuated fire alarm



May 3, 1949 W. J. ELSE SMOKE ACTUATED FIRE ALARM Filed Dec. 11, 1946 Patented May 3, 1949 UNITED STATES PATENT OFFICE SMOKE ACTUATED FIRE ALARM Walter J. Else, Everett, Wash.

Application December 11, 1946, Serial No. 715,441

2 Claims. 1

This invention relates to devices for signalling the presence of fire, and more particularly, to devices of this character which are actuated by smoke.

An important object of the invention is to provide a device of the character described embodying the use of a beam of light projected across an area through which smoke may pass in the event of a fire, the alarm used in combination with the device being actuated by the smoke interrupting the beam.

Another important object of the invention is to provide a device of this type in which means are provided for protecting the beam of light, and the members required in conjunction therewith, from interference by foreign objects, thus effectively sealing the beam from interruption, except by smoke.

With the foregoing and other objects in view which will appear as the description proceeds, the invention consists of certain novel details of construction and combinations of parts, hereinafter more fully described and pointed out in the claims, it being understood that changes may be made in the construction and arrangement of parts without departing from the spirit of the invention as claimed.

Referring to the drawing;

Figure 1 is a side elevational view of the device, with lens holders and a protective screen embodied in the invention shown in longitudinal section.

Figure 2 is a view taken on line 2-2 of Figure 1.

Figure 3 is a diagrammatic view illustrating an electrical circuit, used for actuating an alarm upon the presence of smoke.

Referring to the drawing in detail, the invention embodies an elongated base 5 having a flat supporting surface on which the device is mounted, the base being of any desired length. Brackets 6 support the base 5 horizontally inthe embodiment of the invention herein described, but the base may be mounted with is supporting surface on other than a horizontal plane, its main purpose being to provide a rigid supporting surface for maintaining the parts of the device in fixed relationship. It will be seen therefore, that the base 5 may in fact be formed of separate fixedly mounted members, particularly where the portions of the device supported thereby are a considerable distance apart.

Adjacent one end of the base 5 is mounted a support I for an electric lamp 8, which is preferably of the concentrated-filament sphericalbulb type used in automobile head lamps, and a holder 9 which has an outwardly extended substantially cylindrical portion, for a light-projecting lens.

Extending through the support I, and supplying power to the lamp 8 is an electric cord l0 leading to an ordinary house circuit (not shown) On the other end of the base 5 is mounted a housing II for a photoelectric cell [2, the cell being mounted in a holder l3, formed similarly to the holder 9, for a light-collecting lens.

The lens holders 9 and I3 are held in the support I and housing H in opposing fixed coaxial alignment, so that a beam of light projected from the holder 9 will be directed accurately to the holder [3.

Having its end edges secured to the opposing circular edges of the holders 9 and I3, and extending between the holders, is a cylindrical protective screen 14 of wire mesh material or the like, which is adapted to permit the entry of smoke, but which excludes interfering foreign objects or the like.

In the holder 9 is mounted the light-projecting lens l5 which is adapted to focus and project a beam issuing from the lamp 8, said beam being projected to the light-collecting lens l6 mounted in the holder l3.

In the embodiment of the invention described herein, the electric cord ll] through which power is supplied to the device is shown as leading from an ordinary house circuit, and passes through a step-down transformer I! in order to effect the necessary reduction of current required for illumination of a lamp of the type described. However, it is pointed out that the power supplied to the device may be derived if desired from batteries or the like.

In the diagrammatic illustration shown in Fi ure 3, of a possible circuit used in connection with the device, current passing through the cord [0 supplies power to the lamp 8, throwing a beam which is received by the photoelectric cell [2, the cell I2 being connected in circuit to a house circuit or other power supply, and to a relay 18. The relay I8 is adapted when energized to close the switch l9 which normally is held in withdrawn position by the spring 20. The switch, closing, completes a circuit to which is attached an alarm 2 I.

In this connection, it is pointed out that the sensitivity of the device to smoke density is capable of being adjusted as desired. Such other electrical devices or connections, as, for example, resistors, condensers, thyratron tubes, or additional transformers, may also be used, without departing from the spirit of the invention as claimed, and may as desired be positioned within the housing ll.

Further, the device is adapted to be of any desired length or mounting, and may be connectable to various types and numbers of alarms as desired, either as a unit or as part of a system.

In operation of the device, smoke caused by a fire will pass freely through the screen inter-1 rupting the beam projected through the lens I5 and having the efiect on the photoelectric cell l2 of changing the impedance thereof, thereby energizing the relay I8 and closing (oropening, if the circuit is so arranged) the alarm circuit Suitable means are embodied in the device by use of the protective screen ,to prevent the admission of interfering elements, preventing the setting off of a false alarm.

What is claimed is: v

1 In a fire alarm device, the combination, with a pair of spaced holders, a light source carried by one holder, a photoelectric cell carried by the other holder, and an alarm in circuit with the light source and photoelectric cell and adapted to be actuated by smoke passing between the source and cell, of a means for permitting smoke to pass freely between the holders while yet preventing the passage ofany solid matter, said means comprising a protective guard formed of open mesh screen wire material throughout, and secured at its ends to the respective holders and extended therebetween.

2. In a fire alarm device, the combination, with a pair of spaced holders each having a cylindrical end, a light source carried by one holder, a photoelectric cell carried by the other holder, and an alarm in circuit with the light source and photoelectric cell and adapted to be actuated by smoke passing between the source and cell, of a means for permitting smoke to pass freely between the holders. while preventingv the passage of any solid matter, said meanscomprising a protective guard of open mesh screen wire material formed into a cylinder, said cylinder being secured at its ends to the respective cylindrical ends of the holders and being extended therebetween.

WALTER J. ELSE.

REFERENCES CITED The following references are of record in the file, of this patent;

UNITED- STATES PATENTS 

